- Author: Kathy Keatley Garvey
His seminar, to be both in-person and virtual, begins at 4:10 p.m., Pacific Time in 122 Briggs Hall. The Zoom link is https://ucdavis.zoom.us/j/99515291076.
"From the moment of initial encounter with an insect herbivore, a suite of inducible plant defenses are triggered; however, the molecular mechanisms for recognition and response are not highly studied," Steinbrenner writes in his abstract. "Specific molecular patterns from insects can serve as elicitors of defense responses on host plants, but precise receptors mediating such responses have remained elusive. We recently identified a cell surface receptor, Inceptin Receptor (INR), which detects a set of ubiquitous peptide fragments found in the oral secretions of Lepidopteran larval herbivores. INR is specific to select legume species and may structure insect host range across this plant family. We hypothesize that INR serves as a recently evolved and highly potent mechanism to perceive a specific danger signal, above and beyond cues associated with generic tissue damage. I will discuss our recent transcriptiomic characterization of inceptin responses in bean and cowpea, highlighting strong anti-herbivore defense outputs which occur after inceptin treatment but not wounding alone. I will also compare plant responses to herbivory with well-characterized pathways mediating recognition of microbial pathogens."
Steinbrenner focuses his research on cell and molecular biology, genetics and genomics, and plant biology. He holds a bachelor of science degree in biology from Tufts University (2010) and a doctorate from UC Berkeley in plant biology (2015). He was awarded a Howard Hughes Medical Institute Postdoctoral Fellowship of $180,000 in 2016 and studied with Eric Schmelz at UC San Diego.
The Steinbrenner lab studies the molecular bases of plant immunity to pathogens and pests. "We are specifically interested in recognition and signaling functions of cell surface receptors and evolutionary processes driving novel immune specificity," he says on his website.
Steinbrenner served as the lead author of a paper published Nov. 23, 2021 in the Proceedings of the National Academy of Sciences on how cowpea plants detect that they're being eaten by caterpillars. In the article, A Receptor-Like Protein Mediates Plant Immune Responses to Herbivore-Associated Molecular Patterns, scientists from the University of Washington and UC San Diego reported that the cowpea plants harbor receptors on the surface of their cells that can detect a compound in caterpillar saliva and initiate anti-herbivore defenses.
"Despite chemical controls, crop yield losses to pests and disease generally range from 20-30 percent worldwide," Steinbrenner related in a University of Washington news release. "Yet many varieties are naturally resistant or immune to specific pests. Our findings are the first to identify an immune recognition mechanism that sounds the alarm against chewing insects.”
Wrote UW science writer James Urton: "The team showed that, in response to both leaf wounds and the presence of a protein fragment specific to caterpillar saliva, the cowpea's INR protein boosts the production of ethylene, a hormone that plants often produce in response to munching by herbivores and other types of environmental stress. The protein fragment in caterpillar spit that elicited this response, Vu-IN, is actually a fragment of a cowpea protein, which gets broken down by the caterpillar as it dines on cowpea leaves." (See full article.)
Nematologist Shahid Siddique, assistant professor, UC Davis Department of Entomology and Nematology, coordinates the Wednesday seminars. For any Zoom technical issues, contact him at ssiddique@ucdavis.edu.
- Author: Rachael Freeman Long
Field trials in the Central Valley with two new varieties of blackeye beans, CB74 and CB77, show impressive resistance to cowpea aphids compared to standard CB46, CB5, and CB50 lines. Four varieties of blackeyes including CB46, CB77, CB74, and CB5 were seeded into a blackeye CB50 field, in single lines on 30-inch beds in the Sacramento Valley in May 2020 (Photo 1). By mid-summer, CB50, CB46, and CB5 were heavily infested with aphids (photo 2), whereas CB74 and CB77 were clean (photo 3).
Cowpea aphids are serious insect pests of blackeyes. These aphids can quickly colonize plants and cause injury by direct feeding and injecting toxic saliva into plants, leading to stunted growth or death of plants. Sticky honeydew released by the aphids can stimulate black mold growth on plants, reducing photosynthesis and plant health. Cowpea aphids also vector a number of viral mosaic diseases that can cause serious losses in many crops. Biological control cannot be relied on because natural enemies often appear when cowpea aphid infestations are already high and causing serious damage. Applying pesticides early in the season prevents cowpea aphid infestations but beneficial insects can be destroyed, leading to outbreaks of other insect pests. Thus, the development of cowpea aphid resistant blackeye lines is an important breakthrough in managing this pest.
Blackeye beans, also known as cowpeas, or blackeye peas in southern states, are an important food crop worldwide. In California, about 8,000 acres are grown annually for dry or canned blackeye bean markets. These new blackeye bean lines are being developed by the UC Riverside blackeye breeding program, led by Drs. Phil Roberts and Bao Lam Huynh, with support from the California Dry Bean Advisory Board and the US AID Feed the Future Innovation Lab for Legume Systems Research (formerly Innovation Lab for Collaborative Research on Grain Legumes). The aphid resistance and other traits have been introgressed into California Blackeye elite backgrounds using natural selection and new molecular markers to expedite the breeding process. Compared to standard varieties, CB74 and CB77 also have more stable yields resulting from heat tolerance, better tolerance to lygus bugs, and equivalent resistance to Fusarium wilt and root-knot nematodes.
Blackeye variety observation trials are being conducted in fields by UCCE Farm Advisors Rachael Long, Sarah Light, and Nick Clark in the Sacramento and San Joaquin Valleys, in collaboration with local farmers. More information on blackeye beans can be found in the Blackeye bean production manual for California, UC ANR 21518, http://beans.ucanr.edu/files/226601.pdf. The lead UC bean breeders hope to have these lines available to farmers within the next few years.
- Author: Jeannette E. Warnert
By comparing the DNA from cowpea plants that did poorly in low water conditions with those that did well, an African scientist studying in the Netherlands has traced the location of drought tolerance on the cowpea genome, according to a press release from the International Institute of Tropical Agriculture posted yesterday on SeedQuest.com.
The research, conducted at Wageningen University, will help breeders and farmers produce crops with higher yields despite the changing climate. Cowpea is an important food source in arid areas of West Africa, where over 200 million Africans eat the legumes and feed the tops to their cattle.
The story said similar work on the cowpea genome was reported by researchers at UC Riverside and scientists at the two institutions are comparing notes on the outcomes of their research to see areas of agreement.“If both parties are able to find areas of agreement or concurrence, such areas of the genome would be of immense benefit when marker assisted selection is to be applied in cowpea breeding," the release quoted cowpea breeder Christian Fatokun, who supervised the work for IITA. "So what will take about 10 years to accomplish could be done in three years or even less."
Because cowpea is traditionally cultivated on small farms, very little detailed research into the crop has been conducted, the release said. But that is now changing.
Research to increase cowpea yield is led by UC Riverside and supported through the Generation Challenge Program with funding from the Bill and Melinda Gates Foundation. More on the UC Riverside cowpea genome mapping program is available in this October 2009 news release.